Unit 8 - Volcanoes Flashcards
(21 cards)
What are volcanoes fueled by?
Magma
What is magma?
slushy mixture of molten rock, mineral crystals and gases
What is volcanism?
All processes associated with the discharge of magma, hot fluids, ash and gases
Where do volcanoes form?
Convergent and divergent boundaries
Where is convergent volcanism found?
Subduction zones
How do subduction zone volcanoes form?
As the oceanic plate sinks, it releases water that will melt the overlying rock.
What are the 3 types of volcanism?
Convergent, divergent, hotspot
What does divergent volcanism create?
Seafloor spreading
What does hotspot volcanism produce?
Chains of islands
What are the main 4 parts of a volcano?
Crater, Conduit, magma chamber, vent
What is a collapsed volcano called?
Caldera
What are the 3 types of volcanoes?
Shield, Cinder Cone, composite
What are the features of a shield volcano?
Long gentle slopes
Composed of solidified basaltic lava
Quiet eruptions
What are the features of a Cinder cone volcano?
Smallest, steepest slopes, composed of fragments of basaltic lava, explosive eruptions
Where do cinder cone volcanoes form?
The edges of larger volcanoes
What are the features of a composite volcano?
Tall, majestic mountains. Composed of layers of rock. Cycle through periods of quiet and loud eruptions.
When do rocks melt?
800-1200 degrees Celsius
What determines the explosivity of magma?
Water, dissolved gasses, high silica and viscosity
What are the magma types in order of explosivity?
Rhyolitic, andesitic, basaltic
What is tephra?
materials erupted from a volcano ranging in size from pebbles and ash to boulders and blocks.
What is a pyroclastic flow?
Rapidly moving clouds of tephra mixed with hot, suffocating gases that can move downhill at about 80 km per hour.
